An incommensurate thiourea inclusion compound

X-Ray diffraction studies reveal that the tunnel inclusion compound formed between 1-tert-butyl-4-iodobenzene and thiourea has an incommensurate relationship between the periodicities of the host and guest substructures along the tunnel axis, representing the first reported case of an incommensurate thiourea inclusion compound.     

Vibrational spectroscopy of the multi-anion mineral zykaite Fe4(AsO4)(SO4)(OH)·15H2O-implications for arsenate removal

Some minerals are colloidal and are poorly diffracting. Vibrational spectroscopy offers one of the few methods for the assessment of the structure of these types of minerals. Among this group of minerals is zykaite with formula Fe(4)(AsO(4))(SO(4))(OH)·15H(2)O. The objective of this research is to determine the molecular structure of the mineral zykaite using vibrational spectroscopy. Raman and infrared bands are attributed to the AsO(4)(3-), SO(4)(2-) and water stretching vibrations. The sharp band at 3515 cm(-1) is assigned to the stretching vibration of the OH units. This mineral offers a mechanism for the formation of more crystalline minerals such as scorodite and bukovskyite. Arsenate ions can be removed from aqueous systems through the addition of ferric compounds such as ferric chloride. This results in the formation of minerals such as zykaite and pitticite (Fe(3+), AsO(4), SO(4), H(2)O).     

A vibrational spectroscopic study of the mixed anion mineral sanjuanite Al2(PO4)(SO4)(OH)·9H2O

The mineral sanjuanite Al2(PO4)(SO4)(OH)·9H2O has been characterised by Raman spectroscopy complimented by infrared spectroscopy. The mineral is characterised by an intense Raman band at 984 cm(-1), assigned to the (PO4)3- ν1 symmetric stretching mode. A shoulder band at 1037 cm(-1) is attributed to the (SO4)2- ν1 symmetric stretching mode. Two Raman bands observed at 1102 and 1148 cm(-1) are assigned to (PO4)3- and (SO4)2- ν3 antisymmetric stretching modes. Multiple bands provide evidence for the reduction in symmetry of both anions. This concept is supported by the multiple sulphate and phosphate bending modes. Raman spectroscopy shows that there are more than one non-equivalent water molecules in the sanjuanite structure. There is evidence that structural disorder exists, shown by the complex set of overlapping bands in the Raman and infrared spectra. At least two types of water are identified with different hydrogen bond strengths. The involvement of water in the sanjuanite structure is essential for the mineral stability.     

Raman spectroscopy of newberyite Mg(PO3OH)·3H2O: a cave mineral

Newberyite Mg(PO3OH)·3H2O is a mineral found in caves such as from Moorba Cave, Jurien Bay, Western Australia, the Skipton Lava Tubes (SW of Ballarat, Victoria, Australia) and in the Petrogale Cave (Madura, Eucla, Western Australia). Because these minerals contain oxyanions, hydroxyl units and water, the minerals lend themselves to spectroscopic analysis. Raman spectroscopy can investigate the complex paragenetic relationships existing between a number of 'cave' minerals. The intense sharp band at 982 cm(-1) is assigned to the PO4(3-)ν1 symmetric stretching mode. Low intensity Raman bands at 1152, 1263 and 1277 cm(-1) are assigned to the PO4(3-)ν3 antisymmetric stretching vibrations. Raman bands at 497 and 552 cm(-1) are attributed to the PO4(3-)ν4 bending modes. An intense Raman band for newberyite at 398 cm(-1) with a shoulder band at 413 cm(-1) is assigned to the PO4(3-)ν2 bending modes. The values for the OH stretching vibrations provide hydrogen bond distances of 2.728 ? (3267 cm(-1)), 2.781 ? (3374 cm(-1)), 2.868 ? (3479 cm(-1)), and 2.918 ? (3515 cm(-1)). Such hydrogen bond distances are typical of secondary minerals. Estimates of the hydrogen-bond distances have been made from the position of the OH stretching vibrations and show a wide range in both strong and weak bonds.     

Synthesis and vibrational spectroscopy of halotrichite and bilinite

The new uranyl complexes with tetradentate unsymmetrical N₂O₂ Schiff base ligands were synthesized and characterized by IR, UV–vis, NMR and elemental analysis. The DMF solvent is coordinated to uranyl complexes. The thermogravimetry (TG) and differential thermoanalysis (DTA) of the uranyl complexes were carried out in the range of 20–700 °C. The UO₂L¹ complex was decomposed in two and the others were decomposed in three stages. Up to 100 °C, the coordinated solvent was released then the Schiff base ligands were decomposed in one or two steps. Decomposition of synthesized complexes is related to the Schiff base characteristics. The thermal decomposition reaction is first order for the studied complexes.     

Molecular structure of Mg-Al, Mn-Al and Zn-Al halotrichites-type double sulfates--an infrared spectroscopic study

Near infrared (NIR), X-ray diffraction (XRD) and infrared (IR) spectroscopy have been applied to halotrichites of the formula MgAl(2)(SO(4))(4)·22H(2)O, MnAl(2)(SO(4))(4)·22H(2)O and ZnAl(2)(SO(4))(4)·22H(2)O. Comparison of the halotrichites in different spectral regions has shown that the incorporation of a divalent transition metal into the halotrichite structure causes a shift in OH stretching band positions to lower wavenumbers. Therefore, an increase of the hydrogen bond strength of the bonded water is observed for divalent cations with a larger molecular mass. XRD has confirmed the formation of halotrichite for all three samples and characteristic peaks of halotrichite have been identified for each halotrichite-type compound. It has been observed that Mg-Al and Mn-Al halotrichite are very similar in structure, while Zn-Al showed several differences particularly in the NIR spectra. This work has shown that compounds with halotrichite structures can be synthesised and characterised by infrared and NIR spectroscopy.     

Formation of an N-formylkynurenine-derived fluorophore and its use for measuring indoleamine 2,3-dioxygenase 1 activity

Indoleamine 2,3-dioxygenase 1 (IDO1) is a tryptophan-catabolizing enzyme whose expression by a broad range of clinical tumors is associated with immunosuppression and poor patient outcome. Here we describe a new fluorescence assay for measuring IDO1 activity suitable for high-throughput screening of compound libraries for novel IDO1 inhibitors. This assay is easy to perform, requiring the addition of only one reagent prior to readout. In place of measuring kynurenine, it uses the in situ formation of an N-formylkynurenine-derived fluorophore (NFKPIP) measured at an excitation wavelength of 400 nm and an emission wavelength of 500 nm. The fluorescence intensity of the NFKPIP formed is directly related to the amount of enzyme activity, and the signal is stable over 8 h. This assay has a lower limit of detection, equating to 153 nM N-formylkynurenine, which is over 30-fold lower than the limits of detection of existing assays for IDO1 activity. When we compared the performance of the new assay with that of the published colorimetric absorbance assay in screening the National Cancer Institute Diversity Set III of 1,597 compounds for IDO1 inhibitors, we obtained an identical list of the 25 most active compounds in the two assays. Although 93 compounds (aldehydes, ketones, and aromatic amines) in the library interfered with the absorbance readout, only 18 compounds (conjugated systems and fused cycles) interfered with the readout of the new fluorescence assay. IC₅₀ values determined using the new assay for three known IDO1 inhibitors—1,4-naphthoquinone, 4-amino-N-(3-chloro-4-fluorophenyl)-N’-hydroxy-1,2,5-oxadiazole-3-carboximidamide and 4-phenyl-1H-imidazole—were consistent with their literature values, further validating the new assay for measuring IDO1 activity.

青海省唐古特铁线莲质量控制标准的研究

目的对青海省唐古特铁线莲质量控制标准进行研究。方法采用薄层色谱法对唐古特铁线莲进行定性鉴定,展开剂为氯仿与丙酮（95：5）,显色剂为10％硫酸甲醇;采用HPLC（Lc-2010HT）法测定唐古特铁线莲中齐墩果酸的含量,色谱柱为PhenomenexLunaCt8（250mm×4．6mm,5Ixm）,流动相为y（乙腈）＋V（0．2％磷酸水溶液）=35＋65,流量为1mL／min,柱温为室温（25℃）,检测波长为205nm。结果薄层色谱鉴定中,供试品色谱与对照品色谱相应的位置上,显示出相同颜色的荧光斑点;齐墩果酸在0．0233—0,7000mg／mL范围内呈良好的线性关系,线性回归方程为Y=2×10-6＋360803,r。=0．9917,RSD为1．61％,并对青海省野生和栽培唐古特铁线莲中齐墩果酸进行了定量分析,结果显示前者平均值为0．1184％、RSD为2．5113％,后者平均值为0．0651％、RSD为2．92％。结论该法操作简单、快速、准确、灵敏、重现性好,可有效控制青海省唐古特铁线莲的质量。     

Pt^＋（^2D）催化H2O和CH4制取水煤气循环反应的理论探究

采用密度泛函理论（DFT）B3LYP方法和非迭代三激发电子相关耦合簇CCSD（T）方法研究了二重态和四重态势能面上由Pt＋（2D,4F）催化H2O和CH4产生水煤气的循环反应.采用分子轨道（MO）理论和自然键轨道（NBO）理论对最低能量路径的反应势能面作了详细的分析说明.应用Kozuch撰写的能量跨度模型（energetic span model）确定了决定循环反应速率的决速过渡态（TDTS）和决速中间体（TDI）,最后计算了催化剂的转化频率（TOF）以评价催化剂的性能.     

Fluorometric Beam Profiling of UV MALDI Lasers

The photon distribution (beam profile) of the laser as projected onto the sample is an important variable in matrix assisted laser desorption ionization mass spectrometry (MALDI-MS). Measurement of the beam profile is, therefore, an important factor within MALDI-MS. In this study a simple, low-cost fluorometric laser beam profiling technique is presented and applied in conjunction with MALDI-MS experiments. A comparison of the beam profile information afforded by a commercial system and the fluorometric method is carried out to determine the variation of beam profile for an Nd:YVO₄ laser operated between 1 and 25 kHz. The beam profile information can be used, in conjunction with corresponding ion yields, to inform MALDI-MS experiments. The fluorometric beam profiling technique is used to obtain information about the beam dimensions as incident upon the MALDI-MS sample plate in-source. These values are compared with equivalent information obtained from ablation of thin film α-cyano-4-hydroxycinnamic acid (CHCA). In this study, area estimation by ablation provided a value 1.6 times smaller than that obtained by the fluorometric method, demonstrating the need for caution when measuring beam profile and, therefore, fluence, in MALDI-MS.